Analysis of Infrared Spectral Radiance of O2 1.27 μm Band Based on Space-Based Limb Detection

Abstract

The infrared spectral radiance of O2 is of great significance for space-based infrared detection. In this work, based on the demand for near-infrared spectral radiance of O2 limb detection, a method of spectral radiance calculation coupled with an atmospheric remote sensing model of limb detection is proposed. According to the selection criteria of fine spectral lines, the most suitable spectral lines of the O2 1.27 μm band for detection are given. Specifically, the limb infrared radiances of the O2 1.27 μm band were simulated by using the spectral line data from the spectral database, and the effects of molecular self-absorption were also considered. Furthermore, the infrared spectral radiance distribution of the O2 1.27 μm band was simulated under the influence of altitude, and finally, the detectability of the 1.27 μm band of O2 molecules was analyzed using the criteria of spectral line selection, radiance intensity, spectral separation range and temperature sensitivity. The calculation results show that the spectral radiance of the 1.27 μm band of O2 molecules first increases and then decreases with the decrease of the limb height, and the radiance reaches the peak value in the range of 40–50 km. In terms of the selection of spectral lines, the two groups of spectral lines R7R7, R7Q8 and R11R11, R11Q12 are most suitable for the limb detection and measurement of the O2 1.27 μm band.

Pressure broadening and narrowing due to oxygen and nitrogen gas mixtures at 1270 nm band: part III

“…Where ΓL is the Lorentzian width, and ΓG is the Gaussian width (Doppler broadening full width). The Voigt FWHM of the spectral line depends linearly on the perturber density or pressure either in the case of self-broadening in pure gas or in the case of broadening by foreign gas [27][28][29][30][31][32][33][34][35][36][37][38][39][40]. The effect of foreign gas such as N2 is assumed to be additive, and the Voigt FWHM contribution may be weighed by the mole fractions ( ) i  of gas mixtures, then the total Voigt FWHM may be written according to this equation (Dalton's law):…”